以硫代苹果酸为掩蔽剂络合滴定法测定铅基合金中的铅

本文提出了一种测定铅基合金中的铝的新方法。用硝酸－硫代苹果酸溶解铅基合金。锡、锑、铜和铋等干扰离子同时被硫代苹果酸掩蔽。加入过量的ＥＤＴＡ标准溶液，在ｐＨ５～６用锌标准溶液回滴过量的ＥＤＴＡ以测定铅。应用本法测定铅基合金标样中的铅，准确度和精密度都令人满意。

Complexometric Determination of Lead in Lead-Base Alloys with Thiomalic Acid as Masking Agent

A new method is proposed for the complexometric determination of lead in lead-base allys.Dissolve the alloys with nitric acid-thiomalic acid, and interfering-ions such as tin, antimony,copper and bismuth etc are masked by thiomalic acid. An excess of standard EDTA is added and the solution is boiled for about 5 min at PH 5-6 hexamine buffer. When hot, titrate the excess EDTA with zinc standard solution using xylenol orange as indicator. With this method, lead in two standard samples of lead-base alloys can be determined with satisfactory accuracy and precision, and the recoveries of standard addition of the third sample are in the range of 99.9%-100.3%.